Marino Tiberi Vipraio, 52, who lived in the central Abruzzo region of Italy, died on Wednesday of a heart attack.
He was buried without religious rights, despite a desperate appeal from his family to the local bishop. vItaly's 400,000 Jehovah's Witnesses have had legal recognition since 1976, but the Catholic Church has always opposed their teachings.
This may appear on the surface to be a local story of a row between a parish priest and members of his congregation, but it underlines real tensions that exist in Italy between the Catholic Church and the Jehovah's Witnesses.
Mr Vipraio's sister insists her brother had no connection to the Jehovah's Witnesses, saying he had been baptised and had received the Sacraments.
However, Mr Vipraio was buried on Thursday without religious rites after the priest, Don Fernando Di Fiore, failed to show up.
The family complained to the local bishop, but he said he could not intervene in a matter of which only the priest knew the full details.
It has emerged that Father Di Fiore recently refused a funeral for a man who had divorced and re-married in a civil service. On that occasion the bishop said the priest had followed church regulations.
The Catholic Church in Italy has opposed Jehovah's Witnesses teachings because, among other things, they reject the doctrine of the Holy Trinity, eternal torment in hell and the immortality of the soul.